IFR adds internal camo detection for the Heli Pilot, allowing it to automatically detect Camo Bloons. It is quite an expensive upgrade, so it's usually wise to hold off purchasing this upgrade until harder camo bloon rounds or if pursuing the Downdraft upgrade.
This upgrade is very useful for Camo Rounds, such as Round 42. It is especially good for Round 78 if upgraded to Apache Dartship.
While this upgrade only adds Camo detection, it inherits the buffs of Bigger Jets, so this can be a good crosspath if Heli speed is necessary.